In the nucleus, inositol-pentakisphosphate 2-kinase (IPPK - also known as IP5-2K) phosphorylates inositol 1,3,4,5,6-pentakisphosphate (I(1,3,4,5,6)P5) to inositol 1,2,3,4,5,6-hexakisphosphate (IP6) (Verbsky et al. 2002, Brehm et al. 2007, Choi et al. 2007).
inositol pentakisphosphate 2-kinase activity of IPPK [nucleoplasm]